SiC substrate defects and III-N heteroepitaxy

Abstract

This study addressed how defects in SiC substrates influence the crystallographic properties of AlGaN/GaN layers deposited by metallorganic vapour phase epitaxy and by molecular beam epitaxy. We employed double crystal reflection x-ray topography using symmetric (0008) and (00012) reflections with CuKα radiation (λ = 1.54 Å) to image dislocations, micropipes, and low angle boundaries in SiC substrates. Lattice strain near the core of a micropipe defect was estimated to be of the order of 10−7. The substrates investigated exhibited radial patterns of strain and, primarily, of tilt of the order of tens of arcsec.